Method of water and flame proofing of cellulose fabric after dyeing



United States Patent 2,991,143' METHOD OF WATER AND FLAME PROOFING F CELLULOSE FABRIC AFI'ER DYElNG Kjell Rosenlind, Winneconne, Wis., assignor to Kimberly- Clark Corporation, Neenah, Wis., a corporation of Delaware No Drawing. Filed Feb. '10, 1958, Ser. No. 714,073 6 Claims. (Cl. 8-48) The present invention is concerned with the manufacture of cellulosic products and more particularly with methods of finishing cellulosic fabrics.

The term cellulosic fabrics as used throughout the present specification and claims is intended to include any fabric containing a substantial proportion of cellulose fibers. r The cellulose may be in the form of a natural cellulose fiber or a reconsituted cellulose fiber but not a modified cellulose fiber such as cellulose acetate fiber.

The finishing processes such as dyeing, impregnation with fireproofing agents and with water repellents, etc. which have been developed for use with woven cotton fabrics have, in general, been found to be unsuitable for the finishing of the non-woven cellulosic fabrics, particularly of the disposable type. Non-woven cellulosic fabrics, such as are describedin United States Patent 2,812,797 may be layers of paper or paperlike material usually prepared from wood cellulose fibers, adhesively attached to a reinforcing layer of relatively strong threads, for example of a synthetic material such as nylon or polyethylene terephthalate fibers. These fabrics are also sometimes known as bonded web fabrics. Because the bulk of the non-woven fabric is a paper or paperlike substance and because the methods of preparing the fabrics are very much simplified over the methods of preparing conventional woven cotton fabrics, the nonwoven fabrics may be made so inexpensively that they can be used for disposable items which may be used but once and then destroyed. The nature of the non-woven fabrics often requires that they be finished as are conventional fabrics by dyeing and impregnation with a fireproofing agent and a water repellent agent and that this finishing either improve the hand, drape and abrasion resistance of the product or at least not be detrimental to these qualities. It is necessary that the finishing costs be proportionate to the cost of manufacture of the nonwoven disposable type fabric so that the total cost of the finished fabric is not prohibitive. The various steps of the finishing operation also must be compatible in that a subsequent step cannot impair the desirable effect obtained in a preceding step and material cannot be combined in a solution if undesirable effects such as precipitate formation are obtained thereby.

The methods which have been developed for the dyeing and other finishing of cotton fabrics are, in general, quite complex and expensive. For example, a dyeing operation with cotton cloth usually requires the immers ion of the cloth in a number of baths some of which may be for substantial periods with the bath maintained at quite high temperatures. The impregnation of cotton cloth with fire-retardants and water repellents also usually requires at least one immersion for each operation and may require additional steps such as curing steps. It is therefore apparent that conventional methods of finishing cotton fabrics are, in general, unsuitable for the finishing of the non-woven cellulosic fabrics of the disposable type.

It is an object of the present invention to provide an improved method of dyeing cellulosic fabrics.

It is an additional object of the present invention to .provide an improved method of impregnating cellulosic fabrics with a fire-retardant and a water repellent which "Will not be detrimental to the hand, the drape, and the fire-retardant and a water repellent of a cellulosic fabric can be accomplished by treating the fabric with only two separate baths. The cellulosic fabric is first treated with a bath containing tannic acid and a basic dye and then treated with a second bath containing the fire-retardent, ammonium sulfamate, the water repellent comprising a wax and aluminum salt emulsion, and an aluminum salt of an aliphatic saturated monocarboxylic acid in an amount suflicient to inhibit the formation of a precipitate. This finishing process is inexpensive, simple and compatible and not only dyes, Waterproofs and flameproofs the fabric, but also improves the hand of the material and its resistance to abrasion.

Basic dyes have little affinity for cellulose fibers. Basic dyes, however, have been used on cotton fabrics by first treating the cotton cloth with a mordant such as a tannic acid bath and then treating the cotton cloth with the dye solution. The conventional process for dyeing cotton cloth with basic dyes as described in Chemistry and Chemical Technology of Cotton, Ward, Interscience Publishers, Inc., 1955, page 236, comprises immersing the cotton cloth in a bath containing 2 to 6 percent tannic acid, at boiling temperature for approximately one hour. The material is then rinsed and treated with a solution of antimony salts or tarter emetic in a concentration about /2 of that used for the tannic acid. The cloth is then treated in the basic color dye bath for a substantial time until complete dyeing is obtained.

The number of steps involved and the severity of the conditions make this conventional dyeing operation unsuitable for use with cellulosic fabrics of the non-woven disposable type.

It has been found that tannic acid and a basic dye can be combined in a single dye bath. Cellulosic fabrics, particularly of the non-woven disposable type, can be satisfactorily dyed by treating the fabric with a single application of this bath. The bath is usually prepared by separately dissolving the tannic acid and the direct dye and then adding the resultant solution to a water bath. Tannic acid or commercial tannic acid mordant preparations such as tannic acid technical may be used. The dye bath should contain between about 0.l-2.0 percent tannic acid. The fastness of the dyed cellulosic fabric to water leaching is particularly susceptible to the tannic acid concentration in the dye bath. For example, samples of a non-woven disposable type cellulosic fabric were given identical treatments in seven dye baths differing only in the tannic acid concentration. The baths contained 0.2 percent of a yellow basic dye, color, index 655 (Auramine). The dyed samples were then evaluated as to fastness to water leaching by identical tests. The results are shown in the following table.

TABLE 1 Tannic Acid Fastness to Bath N o. Concentrate, Water Percent Leaching 1 0 Very oor. 2 0.05 Poor. a 0. 1 P001 to fair. 4 0.2 Fair. 5 0.4 Fair to good. 6 1.0 Good. 7 2.0 Good.

Although any basic dye may be used in the dye bath, the water fastness to leaching obtained may vary to some extent with the individual dyes as illustrated by the following data. Dye baths containing 0.2 percent of the specified basic dye and 0.4 percent of tannic acid were prepared. Identical pieces of a non-woven disposable type cellulosic fabric were then dyed by dipping the cloth in the dye bath maintained at room temperature and immediately removing the cloth from the bath, squeezing out the excess solution, followed by drying. The resultant dyed cloths were then evaluated for fastness to water leaching by identical tests. The results are shown in Table 2.

TABLE 2 Color Mfgrs. Dye Type Color Fastness Index Rating Sevron Red L Poor-Fair. Sevron Orange L. Fair. Sevron Brilliant Red 4G Poor-Fair. Salranine TEx. Con 841 PorFair. Rhodamine 5 G DN E 752 Poor. Rhodamine B M 749 Fair-Good. Paper Blue R Conc..-. 681 Good. Nigeria Black G.X Fair. Methyl Violet S. Cone.-. 680 Good. Basic Brown B.R 332 Poor-Fair. Auramine Cone Fair. Victoria Pure Blue 13.0. Good.

Victoria Green Small Crysta Fair.

'As'shown in Table l the variation in water fastness in individual dyes may be compensated for by changes in the tannic acid concentration in the bath.

Cellulosic fabrics, particularly of the non-woven disposable type, have a much wider field of use if in addition to being dyed, they are impregnated with a fire-retardant agent and a water repellent agent. The use of the less expensive non-durable type of water repellent in combination with the fire-retardant however raises a problem since if the fabric is first impregnated with a water repellent such as a wax and aluminum salt emulsion the water repellency of the fabric tends toprevent the sorption of a fire-retardant such as ammonium sulfamate by treatment with an aqueous bath containing the ammonium sulfamate. In addition, there is a tendency for the water repellent to be leached from the fabric by treatment with the aqueous bath. On the other hand if the fabric is first impregnated with the fire-retardant a subsequent treatment with an aqueous suspension of the water repellent will tend to leach from the fabric the fire-retardant. It would therefore be desirable to combine these two agents in a single bath but the two agents are incompatible in the same bath and the addition of these agents to a single bath, in the quantities normally used, will result in the formation of a very substantial precipitate. It Was found, however, that the incorporation of an aluminum salt of a monocarboxylic saturated aliphatic acid haw'ng not more than two carbon atoms, i.e. aluminum formate or aluminum acetate in the bath would prevent the precipitate formation and permit the compatible dissolution of the ammonium sulfamate and the wax aluminum salt emulsion water repellent.

The amount of aluminum salt depends upon the particular aluminum salt used, the temperature of the bath and the concentration of the water repellent and fireretardant. It has been found that at 80 F. bath temperature aluminum acetate, for example, should be present in an amount at least about percent of the weight of the ammonium sulfamate present and 6 percent of the combined weights of the ammonium sulfamate and the wax and aluminum salt emulsions present.

The dye bath may be used at roomtemperature and it may be applied to the cellulosicfabnic by dipping, padding, printing or other standard dyeing methods.

The effect of an aluminum salt of an aliphatic acid was demonstrated by a number-of experiments inwhich the bath components were combined in difierentproportions in a bath and the resultant precipitate determined. Each component was dissolved or dispersed separately and the components then mixed together in a 200 milliliter aqueous bath of tap water at a temperature of 45-50 F. The components in'Table 3 are shown as percent 'by weight of the total bath. Three minutes after the bath was formed the volume of precipitate formed was measured. The volume of the precipitate as shown in the table is the percentage of the total volume of the bath. The water repellent was Aridex L Conc. a commercial wax and aluminum salt emulsion.

TABLE 3 Bath Number Aridex L Cone.

Percent by weight. 5 10 10 10 10 5 10 10 Ammonium Suliamate do 10 5 20 10 5 10 5 10 Aluminum Acetate .do 0 O 0 1 .5 1 l 2 Precipitate .-Percent by volume 22 35 32 30 0 0 0 As shown by the table the precipitation is completely inhibited by the addition of suflicient aluminum acetate.

A similar set of examples were carried out with-aluminum formate substituted for aluminum acetate but all other conditions the same. The results are shown in the following table.

As shown by this table the same quantity of aluminum formate is less effective than aluminum acetate in inhibiting the precipitation effect.

The tendency for the precipitate to form is decreased at lower temperatures as shown by Table 5. In this table is tabulated the results obtained under conditions identical to those of Table 4 except the components were dissolved in water of the temperature indicated and the bath was maintained at that temperature.

TABLE 5 Bath Number Component Bath Temperature. F-. 160 80 50 Aridex L Conc Percent by wt 10 10 10 10 Ammonium Sulfamate d 10 10 10 10 Aluminum Acetate. d0 2 2 2 2 Precipitate formed "Percent by vol 29 26 17 0 The treatment of a cellulosic fabric with this bath will result in the impregnation of the fabric with the fireretardant agent and the water repellent. The treatment substantially improves the hand of the fabric. It has also been found that treatment with this bath will result in anincrease of up to 50 percent in the abrasion'resistance of cellulosic fabric of the non-woven disposable type. This is an unexpected advantage of the use of a fire-retardant and water repellent bath. The above impregnation is compatible with the above described'dyeing operation. Undyed cellulosic fabrics may however be treated with this bath.

The bath can be prepared by separately diluting the wax and aluminum salt emulsion agent, and dissolving the ammoniumsulfarnate .and the ;aluminum saltof the saturated monocarboxylic acid. The water repellent is comprised of an emulsified parafiin and basic aluminum salt and is of the type described in American Dyestuff Reporter, volume 46, No. 25, page 952, Type No. 2. As described in this article, the general formula for this type of water repellent is given as:

O O G R A1O o o R+ emulsified paraflin-l-basic aluminum salt wherein the basic aluminum salt is from the group consisting of basic aluminum acetate, aluminum diformate, aluminum monostearate, aluminum stearate, and other basic aluminum salts of saturated or unsaturated fatty acids, and R may be H, CH C H or C H where the number of carbon atoms is from 6 to 22. A protective colloid such as degraded glue, gelatin, polyvinyl alcohol and the like may also be included in the mixture. Commercially available water repellent agents of this type such as Aridex L Conc. may be used. The concentrations of the water repellent and fire-retardant agents normally employed when these agents are used in separate baths may be used in the combined bath. Stabilized water repellent agents containing a small amount of a protective colloid also are suitable. Baths containing approximately 10 parts water repellent, 16 parts ammonium sulfamate and 2.4 parts aluminum acetate dissolved in 200 parts water are particularly satisfactory for many fabrics. The cellulosic fabric may be immersed in the bath or other conventional methods of treating the fabric with the bath may be employed. During the bath treatment the temperature is normally below about 100 F., and preferably about 40-80 F. As the temperature of the bath is increased the tendency of a precipitate to form in the bath also increases and it may therefore be desirable to increase the amount of aluminum salt of the aliphatic acid if the bath is to be used at higher temperatures.

Now that the invention has been generally described it may be further illustrated by the following specific example.

Example A basic dye bath was prepared by dissolving 0.2 percent of a methyl violet dye color index 680 and 0.4 percent tannic acid in water at room temperature. A cellulosic fabric comprised of a central layer of nylon net and outer layers of paper of the creped wadding type prepared from wood pulp then was padded in the dye bath. The fabric was removed from the bath and allowed to dry. A second bath was prepared by dissolving 10 parts of a water repellent agent of the wax and aluminum salt emulsion type (Aridex), 16 parts of ammonium sulfamate and 2.4 parts of aluminum acetate in 200 parts of water at a temperature of 80 F. The dyed cellulose fabric was then padded in this second bath and allowed to dry.

It will be apparent from the foregoing description and examples that the process of the present invention may be conveniently employed to dye and/or impart a water repellent and fire-retardant finish to cellulosic fabrics, particularly those of the non-woven disposable type. It is also apparent that numerous modifications can be made 6 without departing from the scope of the present invention.

What is claimed is;

l. A method of finishing a cellulosic fabric substantially of unmodified cellulose comprising dyeing said fabric by treating the fabric with a first bath maintained at room temperature containing a basic dye and 0.1-2.0 percent tannic acid, and then treating the fabric with a second bath maintained at a temperature of less than F. and containing ammonium sulfamate, a water repellent of the wax and aluminum salt emulsion type, and an aluminum salt of an aliphatic acid in an amount sufiicient to prevent formation of a precipitate, said amount being at least about 10% by weight of the ammonium sulfamate and 6% of the combined weight of the ammonium sulfamate and the water-repellent.

2. A method of finishing a cellulosic fabric substantially of unmodified cellulose comprising dyeing said fabric by treating said fabric with a dye bath maintained at room temperature containing about 0.05-l percent of a basic dye, and 0.1-2.0 percent tannic acid and then treating said fabric with a second bath maintained at a temperature of less than 100 F., said bath containing ammonium sulfamate, a water repellent of the wax and aluminum salt emulsion type and an aluminum salt of an aliphatic saturated monocarboxylic acid having not more than 2 carbon atoms in an amount of at least 10% of the weight of the ammonium sulfamate and 6% of the combined weight of the ammonium sulfamate and the water repellent, whereby the formation of a precipitate is prevented.

3. The process of claim 2 wherein the aluminum salt of the aliphatic acid is aluminum formate.

4. The process of claim 2 wherein the aluminum salt of the aliphatic acid is aluminum acetate.

5. A method of finishing a cellulosic fabric substantially of unmodified cellulose comprising dyeing said fabric by dipping the fabric in an aqueous dye bath maintained at room temperature containing 0.05-1 percent of a basic dye and 0.1-2 percent of tannic acid, then dipping the dyed fabric in a second aqueous bath maintained at a temperature of 40-80 F., containing about 10 parts of a water repellent agent of the wax and aluminum salt emulsion type, 16 parts of ammonium sulfamate and 2.4 parts of aluminum acetate in 200 parts of water.

6. A process of finishing a cellulosic fabric substantially of unmodified cellulose which comprises treating said fabric with a bath maintained at a temperature of less than 100 F. containing a water repellent of the wax and aluminum salt emulsion type, ammonium sulfamate and an aluminum salt of an aliphatic saturated monocarboxylic acid having not more than two carbon atoms in an amount sufficient to prevent formation of a precipitate, said amount being at least 10% of the weight of the ammonium sulfamate and 6% of the combined weight of the ammonium sulfamate and the water-repellent.

References Cited in the file of this patent UNITED STATES PATENTS 1,660,167 Kern Feb. 21, 1928 1,780,314 Pickareif Nov. 9, 1930 2,012,686 Leatherman Aug. 27, 1935 2,122,100 Kern June 28, 1938 2,589,953 Miller Mar. 18, 1952 OTHER REFERENCES M. E. Cupery et al.: Ind. Eng. Che., vol. 34, No. 7, p. 794, Thorpes Dictionary of Applied Chemistry, Fourth Edition, Vol. 1, p. 292.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patient No, 2,991,143 July 4, 1961 Kjell Rosenlind It is hereby certified that error appears in :the above numbered patentirequiring correction and that the said Letters Patent should read as corrected below. 1

In the grant, line 1, address of inventor, for "Winneconne, Wisconsin," read Neenah, Wisconsin, in the heading to the printed specification, line 4, for "Winneconne, Wis, read Neenah, Wis. column 6, line 11, for "by" read of the Signed and sealed this 2nd day of January 1962e (SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

1. A METHOD OF FINISHING A CELLULOSIC FABRIC SUBSTANTIALLY OF UNMODIFIED CELLULOSE COMPRISING DYEING SAID FABRIC BY TREATING THE FABRIC WITH A FIRST BATH MAINTAINED AT ROOM TEMPERATURE CONTAINING A BASIC DYE AND 0.1-2.0 PERCENT TANNIC ACID, AND THEN TREATING THE FABRIC WITH A SECOND BATH MAINTAINED AT A TEMPERATURE OF LESS THAN 100*F. AND CONTAINING AMMONIUM SULFAMATE, A WATER REPELLENT OF THE WAX AND ALUMINUM SALT EMULSION TYPE, AND AN ALUMINUM SALT OF AN ALIPHATIC ACID IN AN AMOUNT SUFFICIENT TO PREVENT FORMATION OF A PRECIPITATE, SAID AMOUNT BEING AT LEAST ABOUT 10% BY WEIGHT OF THE AMMONIUM SULFAMATE AND 6% OF THE COMBINED WEIGHT OF THE AMMONIUM SULFAMATE AND THE WATER-REPELLENT. 